Thanks for your thoughts.
There was no Ritchie in the crew. The crew consisted of F/O Fletcher, Sgt. Nelson, S/L Foster, Sgt. Beesley, F/Sgt. Layne, S/L McKinna, Sgt. Page.
McKenna was a Squadron Leader (S/?) who was killed inside the aircraft, as was Sgt. Page. Squadron Leader Foster was killed after leaving the aircraft.